Year 11 - Science
Newton's Third Law
Forces make things change
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This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
This unit explores forces, interactions, and Newton's laws, including motion, rotation, and momentum. It covers reaction times, stopping distances, and deceleration dangers. Emphasis is on force diagrams, calculations, experiments, and evaluating methods for accuracy and safety.
Lesson Summary
You will learn to draw force diagrams and identify pairs of forces that obey Newton's Third Law.
Key Notes
- Some forces require contact between objects, while others do not.
- Forces are vectors and can be drawn as arrows on diagrams.
- A free body diagram shows all of the individual forces acting on a single object.
- For every force there is an equal sized force acting in the opposite direction.
- Force pairs have the same magnitude and type and act in opposite directions between two objects.
Vocabulary To Learn
- non-contact force: A force that exists between objects, even if they are not touching.
- contact force: A force that exists between objects when they are touching.
- resultant force: The overall effect of a set of forces acting on an object is represented by a single resultant force.
- free body diagram: A diagram showing all of the forces acting on a single object.
- Newton's Third Law: Forces come in equal and opposite pairs, which act on pairs of different objects.
Common Mistakes To Avoid
- Pupils may regard force as a property of an object, expressing ideas such as 'the object has a force' and 'the object runs out of force'.
3 Quick Questions (With Answers)
1. Explain the scientific idea in this lesson using two key points.
Some forces require contact between objects, while others do not. Forces are vectors and can be drawn as arrows on diagrams.
2. Define this scientific word and use it in context. 'non-contact force'
A force that exists between objects, even if they are not touching. Include the word in a full scientific explanation, not as a single label.
3. Correct this common scientific misunderstanding.
Mistake: Pupils may regard force as a property of an object, expressing ideas such as 'the object has a force' and 'the object runs out of force'. Correction: Describe forces as interactions between two objects, using the phrasing 'the force of object A on object B'.
More Lessons In This Unit
- Balancing Study Guide
- Changing momentum Study Guide
- Conservation of momentum Study Guide
- Force, mass and acceleration (a = (v – u)/t) Study Guide
- Force, mass and acceleration (a = Δv/t) Study Guide
- Forces in two dimensions Study Guide
- Forces in two dimensions (including resolution of a force) Study Guide
- Moments, levers and gears Study Guide
- Newton's Second Law Study Guide
- Newton's Second Law (including inertia) Study Guide
- Newton's Third Law (with free body diagrams in 2D) Study Guide
- Resultant forces and their effects Study Guide
- Stopping Study Guide
- Stopping (and estimating stopping distances) Study Guide
- Stopping safely Study Guide
- Terminal velocity Study Guide
- Terminal velocity (including graphical representation) Study Guide
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